Hitherto, there is known a variable displacement pump which changes a discharge amount of the pump by changing an inclination angle of a swash plate. For example, Patent Literature 1 discloses a variable displacement pump which sucks and discharges a working fluid by moving a piston inside a cylinder block rotating integrally with a rotation shaft in a reciprocating manner with a stroke in accordance with an inclination angle of a swash plate. The variable displacement pump disclosed in Patent Literature 1 includes a control piston which includes a piston portion pressing the swash plate and controls the inclination angle of the swash plate and a housing which includes a piston accommodation portion accommodating the piston portion. The piston portion presses the swash plate through, for example, a cylindrical roll or the like.